Digenean fauna of the great cormorant Phalacrocorax carbo sinensis [Blumenbach, 1798] in the brackish waters of the Vistula Lagoon and the Gulf of Gdansk [Poland]

The great cormorant Phalacrocorax carbo sinensis (Blumenbach, 1798) is one of the most important birds in the Vistula Lagoon and the Gulf of Gdańsk area. As a typical piscivore the bird plays a significant part in life cycles of parasites in aquatic ecosystems. Within January 2000-June 2001, a complete helminthological examination was performed on great cormorants collected in the nesting area at Kąty Rybackie on the Vistula Spit (80 specimens) and in the Vistula Lagoon (10 specimens). The infection prevalence mean intensity, and intensity range were 92.2%, 376.5, and 1-4524, respectively. The presence of 9 digenean species (Paryphostomum radiatum (Dujardin, 1845), Petasiger exaeretits Dietz, 1909, P. phalacroracis (Yamaguti, 1939), Mesorchis pseudoechinatus (Olsson, 1876), Metorchis xanthosomus (Creplin, 1846), Cryptocotyle concavum (Creplin, 1825), Hysteromorpha triloba (Rudolphi, 1819), Tylodelphys clavata (Nordmann, 1832), and Holostephanus dubinini Vojtek et Vojtkova, 1968) was recorded, P. phalacrocoracis being the most common parasile (prevalence 92.2%, mean intensity 323.8). Tylodelphys clavata proved a parasite new for the great cormorant moreover the records of P. phalacrocoracis, H. triloba, and H. dubinini are the first in Poland, while C. concavinn and M. pseudoechinatus were for the first time recorded in the great cormorant in Poland.